It is the purpose of this project to determine the chromosomal localization of the human globin genes and to analyze the regulation of globin gene expression in somatic cell hybrids. To determine the chromosomal assignments, hybrids between mouse and human fibroblasts are analyzed to obtain a precise estimate of chromosomal composition. DNA extracted from these cells is analyzed to determine the human globin gene content. These studies have resulted in the assignment of the human alpha globin gene to chromosome 16 and the human beta globin gene to chromosome 11. Hybrids between mouse Friend erythroleukemia cells and human cells are analyzed to determine the mechanism of regulation of the human globin genes. Co-expression of human and mouse globin genes has been obtained and further hybrids are under analysis to determine whether both the human beta (adult hemoglobin) and gamma (fetal hemoglobin) are expressed in these hybrid cells. BIBLIOGRAPHIC REFERENCES: Deisseroth, A., Velez, R., Burke, R., Minna, J., Anderson, W.F., and Nienhuis, A.: Extinction of globin gene expression in human fibroblast X mouse erythroleukemia cell hybrids. Somatic Cell Genetics 2: 373-384, 1976. Deisseroth, A., Nienhuis, A.W., Turner, P., Velez, R., Anderson, W.F., Ruddle, F., Lawrence, J., Creagan, R., and Kucherlapati, R.: Localization of the human alpha globin structural gene to chromosome 16 in somatic cell hydrids by molecular hybridization assay. Cell 1977, in press.